Hume is a small
lunar impact crater
An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...
that lies along the eastern limb of the
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
, along the southeast edge of
Mare Smythii. It is located just on the
far side of the Moon, but it is often brought into sight from
Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
due to
libration
In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see ...
. Hume lies just to the west-northwest of the much larger
Hirayama, and to the northeast of the flooded crater
Swasey.
Hume has been flooded by flows of
basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
ic
lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
, leaving only a slender rim projecting above the surface. Its interior floor is level and has the same low
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
as the
lunar mare
The lunar maria ( ; mare ) are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to ...
to the northwest. The rim has a wide gap at the northern end, and the floor lies open to the exterior. This feature is not marked by any overlying impacts of note.
Hume is about 650 meters deep when measured from the high point on the southeast rim to the low point on the crater floor.
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Satellite craters
By convention, these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Hume.
References
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External links
LTO-82A4 Hirayama
— L&PI topographic map
In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but histori ...
Impact craters on the Moon